In medical technics, hoses are used to supply liquid to a patient by infusion or to take liquid from a patient or to convey liquid between apparatuses or machines. In doing so, it is necessary to detect a hose occlusion such as it occurs, for example, if the hose is kinked. Further, it is often necessary to limit the internal pressure of a hose.
From DE 40 13 403 C2, a pressure sensor is known where the hose is compressed between two supporting bodies. The one supporting body forms a stationary abutment and the other supporting body is movable and supported by a force sensor. The force sensor detects the force acting upon the hose. This force is counteracted by the restoring force of the hose and the internal pressure of the hose. To measure the internal pressure with sufficient precision, the utilized hose and its restoring ability have to be known. For detecting the material properties of the hose, a time-consuming comparison measurement is performed. As a rule, however, the material properties of the hose depend on the temperature so that different comparison measurements would have to be conducted at different operational temperatures. The deformation force required for deforming the hose, which is particularly high in the border zones of the hose, superimposes the pressure signal up to the factor 10. Therefore, combined measurements of both forces are very incorrect. Moreover, the deformation force is not constant in time over the period of service of the hose.
A similar pressure sensor where a measurement of the hose properties is made first before the signals of the force sensor are evaluated is described in DE 38 38 689 C1. Here, the restoring forces of the hose are also superimposed by the force generated by the internal hose pressure.
There is a need for a pressure sensor the measuring signals of which are largely independent of the utilized hose and the placement duration thereof. This and other needs are addressed, according to aspects of the invention, with the features set forth herein.